1. Field of the Invention
The present invention relates to an outboard motor having an alternator belt-driven by a vertical engine received in an engine room covered by an engine cover.
2. Description of the Prior Art
Outboard motors generally have a vertical engine received in an engine room covered by a water-proof engine cover. The engine cover has a fresh air intake hole for taking fresh air into the engine room. The fresh air taken into the engine room is fed into an air intake device connected to each combustion chamber of the engine. The vertical engine includes a pulley mounted to the upper end of a crankshaft for driving an alternator via an endless belt trained around the pulley and a driven pulley mounted on the alternator. The pulleys and the endless belt are covered by the engine cover.
One example of the outboard motors is disclosed, for example, in Japanese Patent Laid-open Publication No. 6-33790 entitled "Ship Propulsive Machine". The disclosed ship propulsive machine has a top cowl in which an engine body is received. The top cowl is formed with a fresh air intake hole at which fresh air is taken into an engine room. The fresh air taken into the engine room is drawn into the engine body through an air inlet. An alternator is disposed at a position offset from a path along which the fresh air flows from the fresh air intake hole to the air inlet. The alternator is covered by a water-proof cover only at an upper portion thereof.
In the ship propulsive machine, however, since no consideration is given to exhausting of the stale air from the alternator, effective cooling of the alternator is difficult to achieve. Furthermore, due to hot air tending to fill up the top cowl without venting, the atmospheric temperature inside the engine room readily goes up and thus raises the intake air temperature of the engine. This may form a strong obstruct to the increase of the engine power output.